Steering column module for a motor vehicle

ABSTRACT

The invention relates to a steering column module for a motor vehicle, comprising a steering angle sensor ( 13 ) that is inserted into a module housing ( 1,2 ). The rotor of the steering angle sensor is assigned to a steering column and co-operates with at least one fixed measuring wheel ( 37 ), in which angular modifications of the steering column are registered by electronic measuring sensors ( 22 ), operating as the stator and connected to the vehicle electric system by means of a central printed circuit board ( 6 ). The measuring sensors ( 22 ) are fastened to the printed circuit board ( 6 ) and the measuring wheel or wheels ( 37 ) is/are mounted in a housing ( 38 ) that is fixed to the printed circuit board ( 6 ).

The invention relates to a steering column module for a motor vehiclewith a steering angle sensor that is inserted into a module housing. Therotor of the steering angle sensor is assigned to a steering column andinteracts with at least one fixed measuring wheel, in which changes inthe angle of the steering column are registered by electronic measuringsensors operating as the stator and connected to the on-board vehicleelectrical system via a central printed-circuit board.

From DE 44 28 883 C1, an electrical and/or optical device for motorvehicles is known, which is fixed underneath the steering wheel to astationary holding device arranged on the steering column tube. Theholding device is an integral component of a housing belonging to aseparate switch. A steering column lining is arranged on the holdingdevice. The holding device carries a connecting device formed as aspiral cable cassette, as well as a steering angle sensor provided witha printed-circuit board. The connecting device is mounted on the side ofa housing arrangement of the steering angle sensor assigned to thesteering wheel, and the fixed housing part of the connecting device isscrewed onto the holding device. The rotatable housing part of theconnecting device engages with a region formed as an aperture andoperating as a rotor into a circular groove in the housing arrangementof the steering angle sensor.

Furthermore, DE 197 55 094 A1 discloses a steering column module towhich is assigned a unit comprising an electrical connecting device anda steering angle sensor. The connecting device is arranged in a housingsection, which forms a cover for the stator of the steering angle sensorfixed on a printed-circuit board, wherein the printed-circuit board isformed as a base closing the cover.

The previously explained steering angle sensors each work with anoptical detection device, which permits sufficient distance to therotor. This distance is necessary because the rotor assigned to thesteering column has a relatively non-circular movement, which must becompensated together with other installation-specific tolerances.

In addition, from practice, a steering angle sensor is known, whichcomprises a rotor that is fixed to the steering column and thatinteracts with a stator. The stator is built as a module and comprisesin addition to mechanical components, also a printed-circuit board withmeasurement electronics and transmission electronics for coupling to thevehicle electrical system, wherein the signals of the measurementelectronics are transmitted to a central printed-circuit board of thesteering column module and from there to the vehicle electrical system.Thus, both the printed-circuit board of the stator and also theprinted-circuit board of the steering column module is twice equippedwith partially identically components. Finally, two printed-circuitboards necessary for the signal transmission are to be fabricated andassembled.

The problem of the invention is to design a steering column module ofthe type mentioned in the introduction, which is manufacturedeconomically with a reliable function.

According to the invention, the problem is solved in that the measuringsensors are mounted on the printed-circuit board and the one or moremeasuring wheels are mounted in a housing fixed to the printed-circuitboard.

Due to this measure, the mechanical and the electronic components of thesteering angle sensor are separated. The mechanical components of thesteering angle sensor, namely the one or more measuring wheels and therotor, are assigned to the housing or the steering column and theelectronic components, namely the measuring sensors and optionalevaluation electronics, are arranged on the central printed-circuitboard, wherein the printed-circuit board is connected to othercomponents, for example, a flat spiral spring and steering columnswitches. An additional printed-circuit board for the steering anglesensor is eliminated; therefore, a relatively economical manufacturingof the steering column module is guaranteed. Because the centralprinted-circuit board has all of the components for signal transmissionto the vehicle electrical system, a reliable function of the steeringcolumn module is also guaranteed without extra interfaces.

It is useful if the rotor and the measuring wheel are formed as gears.Thus, engagement of the rotor on the measuring wheel with low frictionand a transfer of the changes in the rotational angle of the steeringcolumn with relatively low play are guaranteed.

Preferably, a first measuring gear drives a second measuring gear withan intermediate wheel between, wherein measuring sensors are assigned toboth measuring gears. Through this gearing, a certain ratio is realizedwithin the steering angle sensor, by means of which even very smallchanges in the rotational angle of the steering column can be detectedwith a relatively high accuracy.

Preferably, each of the first measuring gear and the second measuringgear has a measuring magnetic ring inserted on the end and interactingwith the measuring sensors formed as stray field sensors. It is usefulif each of the measuring gears comprises a shielding sheet for themeasuring magnetic ring. Thus, the steering angle sensor works accordingto the so-called Stegmann system, in which one magnet is assigned toevery two stray field sensors, Hall sensors. Advantageously, themeasuring sensors extend into the housing in a position directed towardsthe measuring wheels.

In order to not transfer the non-circular movement of the steeringcolumn to the measuring wheels, according to an advantageousconfiguration of the invention, there is a tolerance compensation devicearranged in the housing between the rotor and the first measuring geardriven by the rotor.

Preferably, the tolerance compensation device comprises a compensationgear, which engages both the rotor and also the first measuring gear ina spring-loaded way. Because the distance between the steering columnand the tolerance compensation device fluctuates and nevertheless anoise-free interaction between the rotor and the measuring gear must beguaranteed, the spring-loaded compensation gear is provided, which ismounted flexibly and assumes a position corresponding to the appropriatedistance between the steering column and the tolerance compensationdevice, wherein the rotor formed as a gear provides for a nearly directdrive of the compensation gear.

In order to be able to change the position of the compensation gearwithin certain limits, advantageously the compensation gear is mountedwith teeth exposed in regions in a cage, which is engaged at one end bya tension spring, whose other end is fixed to the housing. The tensionspring realizes the positioning of the compensation gear both on therotor and also on the measuring gear.

For guaranteeing a compact structure, it is useful if the housingassembled from a cover and also a base supports the cage of thecompensation gear, the two measuring gears, as well as the intermediatewheel.

Preferably, the cover has a support bolt for the intermediate wheel,whose free end engages in a corresponding bore hole of the base. Forachieving a relatively low assembly expense, the support bolt isinjection molded on the cover and thus manufactured together with thispiece in one manufacturing process.

Furthermore, it is necessary to provide supports for the measuringgears. For this purpose, guide holes spaced apart from each other forreceiving support axles for the two measuring gears are preferablyformed in the cover and engage in corresponding openings of the base.

To achieve a relatively simple and secure fixing of the housing,preferably the cover has clip arms for fixing the housing on theprinted-circuit board.

So that the measuring sensors arranged on the central printed-circuitboard are led into the region of the measuring gears, advantageously thebase is provided in the region of the measuring magnet rings of themeasuring gears with two recesses that are offset relative to each otherand that project through the measuring sensors. Preferably, themeasuring sensors are coupled for signal evaluation via theprinted-circuit board with an on-board vehicle computer. Preferably, theprinted-circuit board comprises a bus interface for connecting to theon-board vehicle computer.

Preferably, the rotor is assigned to a cover covering a flat spiralspring in a module housing top part. As a rotatable component spanningthe flat spiral spring, the cover completes the performed changes inrotational angle synchronously with the steering wheel and thus with thesteering column. Thus, the rotor changes its position to the same extentas the steering column, which is why exact measurement values aredetected in terms of the change in rotational angle.

It is understood that the previously mentioned and subsequent featuresstill to be explained can be used not only in the indicated combination,but also in other combinations. The scope of the present invention isdefined only by the claims.

The invention is explained in more detail in the following using anembodiment with reference to the associated drawings. Shown are:

FIG. 1, an exploded view of a steering column module according to theinvention,

FIG. 2, an enlarged exploded view of the detail II from FIG. 1, and

FIG. 3, an enlarged exploded view of the detail III from FIG. 2.

A steering column module comprises a module housing assembled from amodule housing top part 1 and a module housing bottom part 2, wherein acylindrical recess 3 for fixing the steering column module to a(not-shown) steering column tube of a motor vehicle is formed on themodule housing bottom part 2. Furthermore, the module housing bottompart 2 has clip arms 4, which are on the edges and which engage incorresponding clip openings 5 of the module housing top part 1 forassembling the module housing bottom part 2 and the module housing toppart 1. The module housing bottom part 2 receives a centralprinted-circuit board 6, which is coupled to an on-board vehicleelectrical system, as well as an on-board vehicle computer of the motorvehicle. The module housing top part 1 gripping over the module housingbottom part 2 at the edges is provided with a recess 12 for receiving aflat spiral spring, which couples electrical components assigned to thesteering wheel with the on-board vehicle electrical system via theprinted-circuit board 6.

The printed-circuit board 6 has a cylindrical opening 8 aligned with therecess 3 of the module housing bottom part 2, as well as with a hole 7of the module housing top part 1 for passing through a (not-shown)steering column, whose free end is connected to a steering wheel abovethe module housing top part 1. Furthermore, the printed-circuit board 6is provided with connections 9 for (not-shown) steering column switches,whose operating elements project through holes 10 of the module housingtop part 1. Furthermore, the printed-circuit board 6 is connected to anignition lock, which is inserted into an opening 11 formed in the modulehousing top part 1.

In order to determine a relative change in the rotational angle of thesteering wheel relative to the steering column module, between theconnecting device and the module housing top part 1 of the steeringcolumn module there is a steering angle sensor 13, which essentiallycomprises a (not-shown) rotor formed as a gear and a measuring wheel 37formed as a first measuring gear 27, wherein measuring sensors 22 areassigned to the first measuring gear 27. The rotor connects to thesteering column.

The measuring wheel 37 assigned to the rotor is mounted in a housing 38,which is assembled from a cover 15 and a base 16 clipped to the cover.Centering pins 17, which are spaced relative to each other and whichengage in corresponding centering holes 18 of the printed-circuit board6, are formed on the base 16. For fixing the housing 38, the cover 15 isprovided with clip arms 19 to be inserted into clip recesses 20 of theprinted-circuit board 6. Furthermore, the base 16 has recesses 21, inwhich measuring sensors 22, which are fixed to the printed-circuit board6 and which are formed as stray field sensors, so-called Hall sensors,extend into the housing 38. Due to the assignment of the measuringsensors 22 to the printed-circuit board 6, the electrical/electroniccomponents and the mechanical components of the steering angle sensor 13are separated.

For detecting a change in the rotational angle of the steering column,the rotor drives a compensation gear 23, which is assigned to atolerance compensation device 14 and which is mounted floating in thehousing 38 via a cage 24. One end of a tension spring 25, whose otherend is fixed to a retaining pin 26 formed on the cover 15, is fixed onthe cage 24. Through the floating, spring-loaded arrangement of thecompensation gear 23, a tolerance compensation between the rotor, whichexhibits a non-circular movement due to the manufacturing and support ofthe steering column, and the housing 38 is guaranteed. The compensationgear 23 engages the first measuring gear 27, which carries a measuringmagnet ring 28 on the end. An intermediate wheel 29 is set in rotationvia the first measuring gear 27, which in turn drives a second measuringgear 31 likewise provided with an end measuring magnet ring 30.

The first measuring gear 27 and the second measuring gear 31 arearranged on support axles 32, which are inserted with one end into guideholes 33 of the cover 15. With the other end, the support axles 32project into corresponding openings 34 of the base 16. These openingsare formed in the centering pins 17. The intermediate wheel 29 is heldon a support bolt 35, which is assigned to the cover 15 and whose freeend engages in a corresponding hole 36 of the base 16.

The measuring sensors 22, of which two are assigned to each of themeasuring magnet rings 28, 30, detect the rotation of the measuringmagnet rings 28, 30 due to a change in the rotational angle of thesteering column according to the so-called Stegmann system. The signalsof the measuring sensors 22 assigned to the printed-circuit board 6 aretransmitted directly to the on-board vehicle electrical system or theon-board vehicle computer without the intermediate connection of otherelectronic components.

LIST OF REFERENCE SYMBOLS

-   1 Module housing top part-   2 Module housing bottom part-   3 Recess-   4 Clip arm-   5 Clip opening-   6 Printed-circuit board-   7 Hole-   8 Opening-   9 Connection-   10 Through-hole-   11 Opening-   12 Recess-   13 Steering angle sensor-   14 Tolerance compensation device-   15 Cover-   16 Base-   17 Centering pin-   18 Centering hole-   19 Clip arm-   20 Clip recess-   21 Recess of 16-   22 Measuring sensor-   23 Compensation gear-   24 Cage-   25 Tension spring-   26 Retaining pin-   27 First measuring gear-   28 Measuring magnet ring-   29 Intermediate wheel-   30 Measuring magnet ring-   31 Second measuring gear-   32 Support axle-   33 Guide hole of 15-   34 Opening of 16-   35 Support bolt-   36 Hole-   37 Measuring wheel-   38 Housing

1. A steering column module for a motor vehicle, the vehicle having anon-board vehicle electrical system and a steering column relative towhich a steering wheel may rotate so as to exhibit a rotational angle,the steering column module comprising: a steering angle sensor containedwithin a module housing, said module housing configured to be mountedon, and fixed with respect to, said steering column, said steering anglesensor comprising a printed circuit board fixed within said modulehousing and at least one measuring wheel mounted in a wheel housingfixed on the circuit board, said measuring wheel positioned andconfigured to rotate in response to a change in the rotational angle ofsaid steering wheel said circuit board comprising a plurality ofelectronic measuring sensors that are connected to the on-board vehicleelectrical system via the central printed-circuit board and that areconfigured to detect changes in the angle of said measuring wheel.
 2. Asteering column module according to claim 1, wherein the said at leastone measuring wheel is formed as a gear.
 3. A steering column moduleaccording to claim 2, wherein a first measuring wheel drives a secondmeasuring wheel with the intermediate connection of an intermediatewheel, wherein said measuring sensors are assigned to both measuringwheels.
 4. A steering column module according to claim 3, wherein thefirst measuring wheel and the second measuring wheel each have ameasuring magnet ring, which is inserted at the ends and which interactswith the measuring sensors formed as stray field sensors.
 5. A steeringcolumn module according to claim 4, wherein each of the measuring wheelscomprises a shielding plate for the measuring magnet ring.
 6. Steeringcolumn module according to claim 4, wherein the base is provided in theregion of the measuring magnet rings of the measuring wheels with tworecesses, which are offset relative to each other and which projectthrough the measuring sensors.
 7. A steering column module according toclaim 1, wherein the measuring sensors extend into the wheel housing ina position aligned with the at least one measuring wheel.
 8. A steeringcolumn module according to claim 1, wherein a tolerance compensationdevice arranged in the housing is provided so as to cause said at leastone measuring wheel to rotate in response to a change in the rotationalangle of said steering wheel.
 9. A steering column module according toclaim 8, wherein the tolerance compensation device comprises acompensation gear, which connects in a spring-loaded way so as toprovide a mechanical coupling between said steering wheel and saidassigned first measuring wheel.
 10. A steering column module accordingto claim 9, wherein the compensation gear is mounted in a cage exposingits gearing in some regions and one end of this cage engages a tensionspring, whose other end is fixed to the housing.
 11. A steering columnmodule according to claim 9, wherein the housing is assembled from acover and wherein a base supports the cage of the compensation gear andsaid at least one measuring wheel.
 12. A steering column moduleaccording to claim 11, wherein the cover has a support bolt for the atleast one measuring wheel, whose free end engages in a correspondinghole of the base.
 13. A steering column module according to claim 11,wherein said at least one measuring wheel comprises at least twomeasuring wheels, and wherein guide holes, which are spaced apart fromeach other for receiving support axles for the two measuring wheels andwhich engage in corresponding openings of the base, are formed in thecover.
 14. A steering column module according to claim 1, wherein thewheel housing has clip arms for attaching the wheel housing to theprinted-circuit board.
 15. Steering column module according to claim 1,wherein the measuring sensors are coupled with the on-board vehiclecomputer via the printed-circuit board.
 16. Steering column moduleaccording to claim 15, wherein the printed-circuit board comprises a businterface for connecting to the on-board vehicle computer.
 17. Steeringcolumn module according to claim 1, further comprising a cover spanninga flat spiral spring in a module housing top part.